University of Minnesota researchers have counted twice as many emperor penguins in Antarctica as were previously estimated.

Doctoral student Michelle LaRue is perfecting techniques to enhance high-resolution satellite images to accurately counts Emperor Penguins — these are the penguins who sit on their eggs through the cold Antarctic winter, and were the stars of documentary, "The March of the Penguins."

LaRue's images were analyzed by the university's Polar Geospatial Center, which revealed that nearly 600,000 penguins live in Antarctica.

LaRue says she isn't surprised there are more birds than were previously known. Before satellite photography, the only way scientists had been able to count them was from the ground, so they had surveyed only colonies close to research stations.

LaRue's research team also counts Weddell Seal populations.

"There may be a huge population or a huge location where seals haul out and give birth every year that no one knows about just because it's just too difficult to get to," LaRue said.

She said some of the pictures of the emperor penguins were taken during the Antarctic winter, when they congregate in dense colonies to guard their eggs.

"And then as the spring comes and they start hatching their eggs, they still remain in groups but they are spread out a little more, so we were able to count them in this sweet spot in their biology."

The biggest challenge for the penguins and seals is the loss of sea ice due to global warming, LaRue said. Scientists expect the population of emperor penguins to decline by half in the next 50-100 years because of global warming.